1 // SPDX-License-Identifier: GPL-2.0+
2 /* Realtek Simple Management Interface (SMI) driver
3  * It can be discussed how "simple" this interface is.
4  *
5  * The SMI protocol piggy-backs the MDIO MDC and MDIO signals levels
6  * but the protocol is not MDIO at all. Instead it is a Realtek
7  * pecularity that need to bit-bang the lines in a special way to
8  * communicate with the switch.
9  *
10  * ASICs we intend to support with this driver:
11  *
12  * RTL8366   - The original version, apparently
13  * RTL8369   - Similar enough to have the same datsheet as RTL8366
14  * RTL8366RB - Probably reads out "RTL8366 revision B", has a quite
15  *             different register layout from the other two
16  * RTL8366S  - Is this "RTL8366 super"?
17  * RTL8367   - Has an OpenWRT driver as well
18  * RTL8368S  - Seems to be an alternative name for RTL8366RB
19  * RTL8370   - Also uses SMI
20  *
21  * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
22  * Copyright (C) 2010 Antti Seppälä <a.seppala@gmail.com>
23  * Copyright (C) 2010 Roman Yeryomin <roman@advem.lv>
24  * Copyright (C) 2011 Colin Leitner <colin.leitner@googlemail.com>
25  * Copyright (C) 2009-2010 Gabor Juhos <juhosg@openwrt.org>
26  */
27 
28 #include <linux/kernel.h>
29 #include <linux/module.h>
30 #include <linux/device.h>
31 #include <linux/spinlock.h>
32 #include <linux/skbuff.h>
33 #include <linux/of.h>
34 #include <linux/of_mdio.h>
35 #include <linux/delay.h>
36 #include <linux/gpio/consumer.h>
37 #include <linux/platform_device.h>
38 #include <linux/regmap.h>
39 #include <linux/bitops.h>
40 #include <linux/if_bridge.h>
41 
42 #include "realtek.h"
43 
44 #define REALTEK_SMI_ACK_RETRY_COUNT		5
45 
46 static inline void realtek_smi_clk_delay(struct realtek_priv *priv)
47 {
48 	ndelay(priv->clk_delay);
49 }
50 
51 static void realtek_smi_start(struct realtek_priv *priv)
52 {
53 	/* Set GPIO pins to output mode, with initial state:
54 	 * SCK = 0, SDA = 1
55 	 */
56 	gpiod_direction_output(priv->mdc, 0);
57 	gpiod_direction_output(priv->mdio, 1);
58 	realtek_smi_clk_delay(priv);
59 
60 	/* CLK 1: 0 -> 1, 1 -> 0 */
61 	gpiod_set_value(priv->mdc, 1);
62 	realtek_smi_clk_delay(priv);
63 	gpiod_set_value(priv->mdc, 0);
64 	realtek_smi_clk_delay(priv);
65 
66 	/* CLK 2: */
67 	gpiod_set_value(priv->mdc, 1);
68 	realtek_smi_clk_delay(priv);
69 	gpiod_set_value(priv->mdio, 0);
70 	realtek_smi_clk_delay(priv);
71 	gpiod_set_value(priv->mdc, 0);
72 	realtek_smi_clk_delay(priv);
73 	gpiod_set_value(priv->mdio, 1);
74 }
75 
76 static void realtek_smi_stop(struct realtek_priv *priv)
77 {
78 	realtek_smi_clk_delay(priv);
79 	gpiod_set_value(priv->mdio, 0);
80 	gpiod_set_value(priv->mdc, 1);
81 	realtek_smi_clk_delay(priv);
82 	gpiod_set_value(priv->mdio, 1);
83 	realtek_smi_clk_delay(priv);
84 	gpiod_set_value(priv->mdc, 1);
85 	realtek_smi_clk_delay(priv);
86 	gpiod_set_value(priv->mdc, 0);
87 	realtek_smi_clk_delay(priv);
88 	gpiod_set_value(priv->mdc, 1);
89 
90 	/* Add a click */
91 	realtek_smi_clk_delay(priv);
92 	gpiod_set_value(priv->mdc, 0);
93 	realtek_smi_clk_delay(priv);
94 	gpiod_set_value(priv->mdc, 1);
95 
96 	/* Set GPIO pins to input mode */
97 	gpiod_direction_input(priv->mdio);
98 	gpiod_direction_input(priv->mdc);
99 }
100 
101 static void realtek_smi_write_bits(struct realtek_priv *priv, u32 data, u32 len)
102 {
103 	for (; len > 0; len--) {
104 		realtek_smi_clk_delay(priv);
105 
106 		/* Prepare data */
107 		gpiod_set_value(priv->mdio, !!(data & (1 << (len - 1))));
108 		realtek_smi_clk_delay(priv);
109 
110 		/* Clocking */
111 		gpiod_set_value(priv->mdc, 1);
112 		realtek_smi_clk_delay(priv);
113 		gpiod_set_value(priv->mdc, 0);
114 	}
115 }
116 
117 static void realtek_smi_read_bits(struct realtek_priv *priv, u32 len, u32 *data)
118 {
119 	gpiod_direction_input(priv->mdio);
120 
121 	for (*data = 0; len > 0; len--) {
122 		u32 u;
123 
124 		realtek_smi_clk_delay(priv);
125 
126 		/* Clocking */
127 		gpiod_set_value(priv->mdc, 1);
128 		realtek_smi_clk_delay(priv);
129 		u = !!gpiod_get_value(priv->mdio);
130 		gpiod_set_value(priv->mdc, 0);
131 
132 		*data |= (u << (len - 1));
133 	}
134 
135 	gpiod_direction_output(priv->mdio, 0);
136 }
137 
138 static int realtek_smi_wait_for_ack(struct realtek_priv *priv)
139 {
140 	int retry_cnt;
141 
142 	retry_cnt = 0;
143 	do {
144 		u32 ack;
145 
146 		realtek_smi_read_bits(priv, 1, &ack);
147 		if (ack == 0)
148 			break;
149 
150 		if (++retry_cnt > REALTEK_SMI_ACK_RETRY_COUNT) {
151 			dev_err(priv->dev, "ACK timeout\n");
152 			return -ETIMEDOUT;
153 		}
154 	} while (1);
155 
156 	return 0;
157 }
158 
159 static int realtek_smi_write_byte(struct realtek_priv *priv, u8 data)
160 {
161 	realtek_smi_write_bits(priv, data, 8);
162 	return realtek_smi_wait_for_ack(priv);
163 }
164 
165 static int realtek_smi_write_byte_noack(struct realtek_priv *priv, u8 data)
166 {
167 	realtek_smi_write_bits(priv, data, 8);
168 	return 0;
169 }
170 
171 static int realtek_smi_read_byte0(struct realtek_priv *priv, u8 *data)
172 {
173 	u32 t;
174 
175 	/* Read data */
176 	realtek_smi_read_bits(priv, 8, &t);
177 	*data = (t & 0xff);
178 
179 	/* Send an ACK */
180 	realtek_smi_write_bits(priv, 0x00, 1);
181 
182 	return 0;
183 }
184 
185 static int realtek_smi_read_byte1(struct realtek_priv *priv, u8 *data)
186 {
187 	u32 t;
188 
189 	/* Read data */
190 	realtek_smi_read_bits(priv, 8, &t);
191 	*data = (t & 0xff);
192 
193 	/* Send an ACK */
194 	realtek_smi_write_bits(priv, 0x01, 1);
195 
196 	return 0;
197 }
198 
199 static int realtek_smi_read_reg(struct realtek_priv *priv, u32 addr, u32 *data)
200 {
201 	unsigned long flags;
202 	u8 lo = 0;
203 	u8 hi = 0;
204 	int ret;
205 
206 	spin_lock_irqsave(&priv->lock, flags);
207 
208 	realtek_smi_start(priv);
209 
210 	/* Send READ command */
211 	ret = realtek_smi_write_byte(priv, priv->cmd_read);
212 	if (ret)
213 		goto out;
214 
215 	/* Set ADDR[7:0] */
216 	ret = realtek_smi_write_byte(priv, addr & 0xff);
217 	if (ret)
218 		goto out;
219 
220 	/* Set ADDR[15:8] */
221 	ret = realtek_smi_write_byte(priv, addr >> 8);
222 	if (ret)
223 		goto out;
224 
225 	/* Read DATA[7:0] */
226 	realtek_smi_read_byte0(priv, &lo);
227 	/* Read DATA[15:8] */
228 	realtek_smi_read_byte1(priv, &hi);
229 
230 	*data = ((u32)lo) | (((u32)hi) << 8);
231 
232 	ret = 0;
233 
234  out:
235 	realtek_smi_stop(priv);
236 	spin_unlock_irqrestore(&priv->lock, flags);
237 
238 	return ret;
239 }
240 
241 static int realtek_smi_write_reg(struct realtek_priv *priv,
242 				 u32 addr, u32 data, bool ack)
243 {
244 	unsigned long flags;
245 	int ret;
246 
247 	spin_lock_irqsave(&priv->lock, flags);
248 
249 	realtek_smi_start(priv);
250 
251 	/* Send WRITE command */
252 	ret = realtek_smi_write_byte(priv, priv->cmd_write);
253 	if (ret)
254 		goto out;
255 
256 	/* Set ADDR[7:0] */
257 	ret = realtek_smi_write_byte(priv, addr & 0xff);
258 	if (ret)
259 		goto out;
260 
261 	/* Set ADDR[15:8] */
262 	ret = realtek_smi_write_byte(priv, addr >> 8);
263 	if (ret)
264 		goto out;
265 
266 	/* Write DATA[7:0] */
267 	ret = realtek_smi_write_byte(priv, data & 0xff);
268 	if (ret)
269 		goto out;
270 
271 	/* Write DATA[15:8] */
272 	if (ack)
273 		ret = realtek_smi_write_byte(priv, data >> 8);
274 	else
275 		ret = realtek_smi_write_byte_noack(priv, data >> 8);
276 	if (ret)
277 		goto out;
278 
279 	ret = 0;
280 
281  out:
282 	realtek_smi_stop(priv);
283 	spin_unlock_irqrestore(&priv->lock, flags);
284 
285 	return ret;
286 }
287 
288 /* There is one single case when we need to use this accessor and that
289  * is when issueing soft reset. Since the device reset as soon as we write
290  * that bit, no ACK will come back for natural reasons.
291  */
292 static int realtek_smi_write_reg_noack(void *ctx, u32 reg, u32 val)
293 {
294 	return realtek_smi_write_reg(ctx, reg, val, false);
295 }
296 
297 /* Regmap accessors */
298 
299 static int realtek_smi_write(void *ctx, u32 reg, u32 val)
300 {
301 	struct realtek_priv *priv = ctx;
302 
303 	return realtek_smi_write_reg(priv, reg, val, true);
304 }
305 
306 static int realtek_smi_read(void *ctx, u32 reg, u32 *val)
307 {
308 	struct realtek_priv *priv = ctx;
309 
310 	return realtek_smi_read_reg(priv, reg, val);
311 }
312 
313 static void realtek_smi_lock(void *ctx)
314 {
315 	struct realtek_priv *priv = ctx;
316 
317 	mutex_lock(&priv->map_lock);
318 }
319 
320 static void realtek_smi_unlock(void *ctx)
321 {
322 	struct realtek_priv *priv = ctx;
323 
324 	mutex_unlock(&priv->map_lock);
325 }
326 
327 static const struct regmap_config realtek_smi_regmap_config = {
328 	.reg_bits = 10, /* A4..A0 R4..R0 */
329 	.val_bits = 16,
330 	.reg_stride = 1,
331 	/* PHY regs are at 0x8000 */
332 	.max_register = 0xffff,
333 	.reg_format_endian = REGMAP_ENDIAN_BIG,
334 	.reg_read = realtek_smi_read,
335 	.reg_write = realtek_smi_write,
336 	.cache_type = REGCACHE_NONE,
337 	.lock = realtek_smi_lock,
338 	.unlock = realtek_smi_unlock,
339 };
340 
341 static const struct regmap_config realtek_smi_nolock_regmap_config = {
342 	.reg_bits = 10, /* A4..A0 R4..R0 */
343 	.val_bits = 16,
344 	.reg_stride = 1,
345 	/* PHY regs are at 0x8000 */
346 	.max_register = 0xffff,
347 	.reg_format_endian = REGMAP_ENDIAN_BIG,
348 	.reg_read = realtek_smi_read,
349 	.reg_write = realtek_smi_write,
350 	.cache_type = REGCACHE_NONE,
351 	.disable_locking = true,
352 };
353 
354 static int realtek_smi_mdio_read(struct mii_bus *bus, int addr, int regnum)
355 {
356 	struct realtek_priv *priv = bus->priv;
357 
358 	return priv->ops->phy_read(priv, addr, regnum);
359 }
360 
361 static int realtek_smi_mdio_write(struct mii_bus *bus, int addr, int regnum,
362 				  u16 val)
363 {
364 	struct realtek_priv *priv = bus->priv;
365 
366 	return priv->ops->phy_write(priv, addr, regnum, val);
367 }
368 
369 static int realtek_smi_setup_mdio(struct dsa_switch *ds)
370 {
371 	struct realtek_priv *priv =  ds->priv;
372 	struct device_node *mdio_np;
373 	int ret;
374 
375 	mdio_np = of_get_compatible_child(priv->dev->of_node, "realtek,smi-mdio");
376 	if (!mdio_np) {
377 		dev_err(priv->dev, "no MDIO bus node\n");
378 		return -ENODEV;
379 	}
380 
381 	priv->slave_mii_bus = devm_mdiobus_alloc(priv->dev);
382 	if (!priv->slave_mii_bus) {
383 		ret = -ENOMEM;
384 		goto err_put_node;
385 	}
386 	priv->slave_mii_bus->priv = priv;
387 	priv->slave_mii_bus->name = "SMI slave MII";
388 	priv->slave_mii_bus->read = realtek_smi_mdio_read;
389 	priv->slave_mii_bus->write = realtek_smi_mdio_write;
390 	snprintf(priv->slave_mii_bus->id, MII_BUS_ID_SIZE, "SMI-%d",
391 		 ds->index);
392 	priv->slave_mii_bus->dev.of_node = mdio_np;
393 	priv->slave_mii_bus->parent = priv->dev;
394 	ds->slave_mii_bus = priv->slave_mii_bus;
395 
396 	ret = devm_of_mdiobus_register(priv->dev, priv->slave_mii_bus, mdio_np);
397 	if (ret) {
398 		dev_err(priv->dev, "unable to register MDIO bus %s\n",
399 			priv->slave_mii_bus->id);
400 		goto err_put_node;
401 	}
402 
403 	return 0;
404 
405 err_put_node:
406 	of_node_put(mdio_np);
407 
408 	return ret;
409 }
410 
411 static int realtek_smi_probe(struct platform_device *pdev)
412 {
413 	const struct realtek_variant *var;
414 	struct device *dev = &pdev->dev;
415 	struct realtek_priv *priv;
416 	struct regmap_config rc;
417 	struct device_node *np;
418 	int ret;
419 
420 	var = of_device_get_match_data(dev);
421 	np = dev->of_node;
422 
423 	priv = devm_kzalloc(dev, sizeof(*priv) + var->chip_data_sz, GFP_KERNEL);
424 	if (!priv)
425 		return -ENOMEM;
426 	priv->chip_data = (void *)priv + sizeof(*priv);
427 
428 	mutex_init(&priv->map_lock);
429 
430 	rc = realtek_smi_regmap_config;
431 	rc.lock_arg = priv;
432 	priv->map = devm_regmap_init(dev, NULL, priv, &rc);
433 	if (IS_ERR(priv->map)) {
434 		ret = PTR_ERR(priv->map);
435 		dev_err(dev, "regmap init failed: %d\n", ret);
436 		return ret;
437 	}
438 
439 	rc = realtek_smi_nolock_regmap_config;
440 	priv->map_nolock = devm_regmap_init(dev, NULL, priv, &rc);
441 	if (IS_ERR(priv->map_nolock)) {
442 		ret = PTR_ERR(priv->map_nolock);
443 		dev_err(dev, "regmap init failed: %d\n", ret);
444 		return ret;
445 	}
446 
447 	/* Link forward and backward */
448 	priv->dev = dev;
449 	priv->clk_delay = var->clk_delay;
450 	priv->cmd_read = var->cmd_read;
451 	priv->cmd_write = var->cmd_write;
452 	priv->ops = var->ops;
453 
454 	priv->setup_interface = realtek_smi_setup_mdio;
455 	priv->write_reg_noack = realtek_smi_write_reg_noack;
456 
457 	dev_set_drvdata(dev, priv);
458 	spin_lock_init(&priv->lock);
459 
460 	/* TODO: if power is software controlled, set up any regulators here */
461 
462 	priv->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
463 	if (IS_ERR(priv->reset)) {
464 		dev_err(dev, "failed to get RESET GPIO\n");
465 		return PTR_ERR(priv->reset);
466 	}
467 	if (priv->reset) {
468 		gpiod_set_value(priv->reset, 1);
469 		dev_dbg(dev, "asserted RESET\n");
470 		msleep(REALTEK_HW_STOP_DELAY);
471 		gpiod_set_value(priv->reset, 0);
472 		msleep(REALTEK_HW_START_DELAY);
473 		dev_dbg(dev, "deasserted RESET\n");
474 	}
475 
476 	/* Fetch MDIO pins */
477 	priv->mdc = devm_gpiod_get_optional(dev, "mdc", GPIOD_OUT_LOW);
478 	if (IS_ERR(priv->mdc))
479 		return PTR_ERR(priv->mdc);
480 	priv->mdio = devm_gpiod_get_optional(dev, "mdio", GPIOD_OUT_LOW);
481 	if (IS_ERR(priv->mdio))
482 		return PTR_ERR(priv->mdio);
483 
484 	priv->leds_disabled = of_property_read_bool(np, "realtek,disable-leds");
485 
486 	ret = priv->ops->detect(priv);
487 	if (ret) {
488 		dev_err(dev, "unable to detect switch\n");
489 		return ret;
490 	}
491 
492 	priv->ds = devm_kzalloc(dev, sizeof(*priv->ds), GFP_KERNEL);
493 	if (!priv->ds)
494 		return -ENOMEM;
495 
496 	priv->ds->dev = dev;
497 	priv->ds->num_ports = priv->num_ports;
498 	priv->ds->priv = priv;
499 
500 	priv->ds->ops = var->ds_ops_smi;
501 	ret = dsa_register_switch(priv->ds);
502 	if (ret) {
503 		dev_err_probe(dev, ret, "unable to register switch\n");
504 		return ret;
505 	}
506 	return 0;
507 }
508 
509 static int realtek_smi_remove(struct platform_device *pdev)
510 {
511 	struct realtek_priv *priv = platform_get_drvdata(pdev);
512 
513 	if (!priv)
514 		return 0;
515 
516 	dsa_unregister_switch(priv->ds);
517 	if (priv->slave_mii_bus)
518 		of_node_put(priv->slave_mii_bus->dev.of_node);
519 
520 	/* leave the device reset asserted */
521 	if (priv->reset)
522 		gpiod_set_value(priv->reset, 1);
523 
524 	return 0;
525 }
526 
527 static void realtek_smi_shutdown(struct platform_device *pdev)
528 {
529 	struct realtek_priv *priv = platform_get_drvdata(pdev);
530 
531 	if (!priv)
532 		return;
533 
534 	dsa_switch_shutdown(priv->ds);
535 
536 	platform_set_drvdata(pdev, NULL);
537 }
538 
539 static const struct of_device_id realtek_smi_of_match[] = {
540 #if IS_ENABLED(CONFIG_NET_DSA_REALTEK_RTL8366RB)
541 	{
542 		.compatible = "realtek,rtl8366rb",
543 		.data = &rtl8366rb_variant,
544 	},
545 #endif
546 #if IS_ENABLED(CONFIG_NET_DSA_REALTEK_RTL8365MB)
547 	{
548 		.compatible = "realtek,rtl8365mb",
549 		.data = &rtl8365mb_variant,
550 	},
551 #endif
552 	{ /* sentinel */ },
553 };
554 MODULE_DEVICE_TABLE(of, realtek_smi_of_match);
555 
556 static struct platform_driver realtek_smi_driver = {
557 	.driver = {
558 		.name = "realtek-smi",
559 		.of_match_table = realtek_smi_of_match,
560 	},
561 	.probe  = realtek_smi_probe,
562 	.remove = realtek_smi_remove,
563 	.shutdown = realtek_smi_shutdown,
564 };
565 module_platform_driver(realtek_smi_driver);
566 
567 MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
568 MODULE_DESCRIPTION("Driver for Realtek ethernet switch connected via SMI interface");
569 MODULE_LICENSE("GPL");
570